MODULATED MOLECULAR-BEAM STUDY OF GROUP-III DESORPTION DURING GROWTH BY MBE

Direct measurements of Ga and In desorption rates from GaAs and InAs were made using modulated beam mass spectrometry (MBMS). Two distinct temperature dependences of In desorption from InAs were observed. One is shown to be independent of surface In adatom population. The other is shown to be dependent on In adatom population. They are the rate limiting processes at different temperature regions and are independent of one another. We suggest the latter is due to In clusters on the surface. Under As2, Ga desorption is largely dominated by a surface adatom process. However, there is a surface Ga adatom dependent contribution at low temperature under As4.